The parents of murdered skydiver Stephen Hilder were launching a fresh appeal for information today - one week before what would have been their son's 21st birthday.

Mr Hilder plunged 13,000ft to his death over Hibaldstow airfield, north Lincolnshire, on July 4, after both his main and reserve parachutes were sabotaged.

Paul and Mary Hilder hope the appeal, being made in their home town of Hereford, will provide fresh leads for detectives investigating Mr Hilder's death.

Three men, two aged 19 and one aged 24, have been arrested in the weeks following the death and have all been released on police bail pending further inquiries. During the investigation Humberside Police interviewed people in the North East as Mr Hilder had competed in an event at the Border Parachute Centre at Brunton Airfield, Chathill, Northumberland, between Friday May 2 and Sunday May 4.

Mr Hilder was an army officer cadet based at the Royal Military College of Science at Shrivenham, near Swindon. He had been taking part in the National Championships of the British Collegiate Parachute Association.

He had made more than 200 jumps.

Mr Hilder's parents made a public and emotional appeal in July for help in tracking down his killer, as did his girlfriend, Ruth Woodhouse, 24, of Stafford.

His parents said they had been "living through every parent's worst nightmare" following his death.

At the time of their appeal, they said they believed someone in Britain's close-knit skydiving community knew who had sabotaged their son's parachute.

Ms Woodhouse, a student at the Defence Academy in Shrivenham, who met Mr Hilder in January, spoke of her grief at his death.

She said in July: "Somebody has taken this sparkly person from the world in the most awful way."